Airport lighting system



AIRPORT LIGHTING SYSTEM Filed Oct. 26, 1945 5 Shets-She et 1 FIG. I

TALK DIAL I 5 I06 I07 MISCL. LIGHT" RUNWAY LIGHT L952 INTENSITY LIGHTINDIGATING I IN0IcATIIIs I INDIGATING RELAYS 2?? c5: RELAY-S 5|0 RELAYSHOV.[ T

I INVENTOR. HARRY N. NEWSTEDT ATTORNEY Oct. H. N. NEWSTEDT 9 59 AIRPQRTLIGHTING SYSTEM Filed Oct. 26, 1945 5 Sheets-Shet 2 FIG. 2

BEACON LIGHT BOUNDARY LIGHTS MISCL. LIGHT HOV. AG. 2300 v 40 5 LCLONTROLRELAYSJ AC W IN VEN TOR. HARRY N. NEWSTEDT ATTORN EY 1949 H. N. NEWSTEDT9 7 9 AIRPORT LIGHTiNG SYSTEM Filed Oct. 26, 1945 5 Shets-Sheet 3 v zzsm FIG. 5 x

HARRY N. NEWSTEDT ATTORNEY 0st. 25, W49.

Filed Oct. 26, 1945 H. N. NEWSTEDT AIRPORT LIGHTING SYSTEM 5Sheets-Sheet 4 INVENTOR. HARRY N. NEWSTEDT ATTORNEY Get. 25, 1949; H. N.NEWSTEDT 2,486,R

AIRPORT LIGHTING SYSTEM Filed Oct. 26, 1945 5 Sheets-Sheet 5 Tu 1% 54O550-2 56O ATTORNEY Patented Oct. 25, 1949 UNITED STATES ()FFICE maticElectric Laboratories, Inc., Chicago, Ill a corporation of DelawareApplication October 26, 1945, Serial No. 624,776 6 Claims. (01. 177-352)The present invention pertains to airport lighting systems and, moreparticularly, to improved remote control apparatus therefor.

An airport conventionally comprises a flying field having a plurality ofairplane runways thereon, some of the runways being arranged inintersecting relationship with respect to other ones of the runways andin non-intersecting relationship with respect to still other ones of therunways. Illuminating devices of some form are usually provided for thepurpose of lighting the runways when the flying field is not otherwiseclearly visible; and occasionally traffic signals of some form areprovided for the purpose of governing airplane trafiic on the runways.

It has heretofore been proposed to provide switching arrangements, forselectively controlling the illumination of the runways in an airportlighting system of the type noted, which would positively prevent thecontrol of the illuminating means associated with conflicting runways.Such a system has been disclosed .in Ratent 2,296,936, issued to Loganet al. on September 29, 1942.

It is an object of the present invention to provide improved switchingarrangements, for selectively controlling the illumination of therunways in an airport lighting system, which will positively prevent thecontrol of the illuminating means associated with conflicting runways,and which is simpler in construction and operation thanpreviouslyproposed systems.

A further object of the invention is to provide a switching apparatuswhich is responsive to the successive transmission :of a series ofimpulses over a control line to alternately energize and ole-energize acorresponding one of the illuminating means associated with the airport.

Still another object of the invention is to provide a switchingapparatus which is responsive to a series of impulses transmitted over acontrol line to energize a corresponding one of the runway illuminatingmeans, and to prevent control of other ones of the illuminating meansuntil said one illuminating means has been de-energized by thesubsequent retransmission of the corresponding series of impulses.

A still further object of the invention is to provide a switchingapparatus for selectively or simultaneously energizing several differentrun- 2 way illuminating means which is arranged to prevent selectivede-energization of the group of energized runway illuminating means.

A feature of the invention is the provision, in a switching apparatusfor selectively energizing different runway illuminating means to avariable degree from a common source, of means responsive to a selectionfor disabling the source while the selection is completed, wherebysmaller and more economical contactors may be employed.

Other objects and features of the invention will appear upon a furtherperusal of the specification and accompanying drawings, wherein:

Fig. 1 is a schematic diagram of the apparatus which is located in thecontrol tower of the airport;

Fig. 2 is a schematic diagram of the"selecting apparatus, located at acentral switching point, together with the beacon light and boundarylights controlled thereby;

Fig. 3 shows the selecting relays which control the intensity of therunway lights which are ener-- gized;

Fig. 4 shows the selecting relays for controlling the illumination ofthe runways; and

Fig. 5 shows the runway lights and energizing circuits therefor.

All of these figures should be placed side by side in numerical order toform a unified system. Described briefly, the system comprises aselector switch of the Strowger type, located at a central switchingpoint, which is controlled by alternat ing current impulses transmittedover a two wire line from the control tower. This selector switch hasaccess to three groups of selecting relays; one group of which controlsmiscellaneous lights, such as the beacon and-boundary lights; a secondgroup determines which runway, or group of runways, is to beilluminated; and the third group controls the brightness of theenergized runway lights. Each lamp, or group of lamps, is assigned acorresponding two digit number. A further number. is assigned to acombination of the lamps associated with a pair of non-intersectingrunways. The miscellaneous and runway light selecting relays arearranged to alternately energize and de-energize the corresponding lampsin response to the successive selection thereof by the selector switch.The runway light selecting relays are further arranged to prevent a newselection from being made while any runway lights are energized. Boththe light intensity and the runway light selectin relays are arranged toopen a common point in the energizing circuits for the runway lights,during the switching operations resulting from a new selection, wherebythe contactors involved. in these switching operations need not make orbreak energized circuits.

A second selector switch is located in the con- 1 trol tower and isarranged to be operated concurrently with the selector switch at theswitching point under the control of an impulse transmitter, or dial, ofthe type commonly employed in telephone systems. This second selectorswitch has access to three groups of selecting relays, which areduplicates of those provided at the central switching point, and whichcontrol indicating lamps located before the dispatcher to enable him toobserve the operation of the system. Sound powered telephone handsets,employing transmitter and receiver units of the type fully described inPatent 2,241,105, issued May 6, 1941, to A. E. Woodruff et al., areprovided in the control tower and at the switching point i to permitcommunication therebetween over the control line.

The switching point is also arranged to permit testing of the switchingapparatus thereat, by means of an impulse transmitter, independently ofthe control tower.

Referring now to Fig. 1, there is shown a sound powered telephone I00, akey IOI, an impulse transmitter I02, a two-digit selector switch I03,

a telephone ringer I04 and associated alternating current relay I00, andthree groups of indicating relays I05, I05, and I01 together with theindicating lamps controlled thereby. Conductors I08 and I09 extendbetween the control tower and the switching point.

In Fig. 2 there is shown a sound powered telephone 200, a key 20 I, animpulse transmitter 202, a two-digit selector 203, a telephone ringer204 and associated relay 2 20, an alarm relay 2 35 and associated alarmlamp 249, miscellaneous light control relays 250, 255, 200 and 265, andcontactors H and 215 which control the circuits to the beacon light 2'82and the boundary lights 211, respectively, the latter being energizedthrough a constant current transformer 278. The miscellaneous lightcontrol relays are connected to the bank contacts of selector switch 203over cable 205. The light intensity control relays (Fig. 3) and runwaylight control relays (Fig. 4) are similarly connected to the bankcontacts of selector switch 203 over cables 305 and 405, respectively.The last two groups of relays control contactors 510 to 530 and 540 to560, respectively. Contactors 5I0 to 530 control the primary tosecondary turns ratio of current transformer 510 and thus control thebrilliance of runway lamps RI to R3 which are not short-circuited bycontactors 540 to 550. Transformer 510 is energized by the constantcurrent transformer 580 from a source of high voltage alternatingcurrent through contacts of contactor 500.

It will be noted that when the miscellaneous light control relays arerestored the contactors 210 and 215 are operated to energize the beaconlight 2l2 and the boundar lights H1. The corresponding indicating lampsN2 and 21?, respectively, shown in Fig. 1 will also be energized. Inorder to extinguish the beacon light the dispatcher operates key IOI tothe right and then dials the two digit number assigned to the beacon 4light. When key MI is operated to the right it completes a circuit torelay I in series with the impulse transmitter I02. Relay I20 operates,closes a circuit to relay I at contacts I22, and completes a circuit torelay 220 at contacts I2I. The latter circuit may be traced from oneside of the 110 v. A. C. supply through cont-acts IZI, contacts of keyIOI, contacts I4I, over conductor I09, through contacts of key 20I, fullwave rectifier 209 and relay 220, contacts 246, contacts of key 20I,over conductor I08, and through contacts of key I0| to the other side ofthe 110 v. A. C. supply. Relay 220 operates and closes a circuit torelay 225 at contacts 22I. Relays I25 and 225 operate.

The dispatcher now dials the number assigned to the beacon light, whichnumber will be assumed to be 41. When the impulse transmitter I02 isoperated to transmit the first digit, the circuit to relay I20 ismomentaril interrupted four times in succession. Each time that relayI20 restores it opens the circuit to relay 220 at contacts I2I andcloses a circuit to the vertical magnet I05 of the selector switch inseries with relay I30. The latter circuit is completed from groundthrough contacts I22, I26, and normally closed contacts of the verticalofi-normal springs I06, initially, and through make contacts of thevertical off-normal springs I05 and contacts I3I after relay I hasoperated and the vertical off-normal springs have been operated inresponse to the operation of the switch shaft to the first level by thevertical magnet I05. Relay 220' is momentarily restored four times insuccession concurrently with relay I20 causing the vertical magnet 205to step the switch shaft of selector switch 203 to the fourth level. Thecircuits of the selector switch 203 need not be traced since they areidentical to those traced for selector switch I03. Relays I25, I30, 225and 230 are rendered slow to release by copper sleeves placed over theircores so that they remain operated during impulsing. Shortly after theseries of impulses have been transmitted by the impulse transmitter I02,relays I30 and 230 restore to transfer the impulsing circuits of theselector switches from the vertical magnets I05 and 205 to the rotarymagnets H0 and 2 I0, respectively.

When impulse transmitter I02 is again operated to transmit the seconddigit relays I 20 and 220' will each be momentarily released once. Whenrelay I20 restores it 'completes a circuit from ground through contactsI22, I26, make contacts of the vertical off-normal springs I06, contactsI3I, and through relay I and rotary magnets IIO to battery. Relay 220completes a similar circuit to rotary magnets 2 I0 in series with relay235. Relays I35 and 235 operate and open points in the circuits towipers I31 and 231, respectively. Rotary magnets I I0 and 2 I0 operateto rotate the wipers I3! and 231, respectively, to the first bankcontacts of the fourth level. Relays I35 and 235 restore shortly afterrelays I20 and 220 have reoperated. When relay 235 restores it completesa circuit from ground through contacts 22I and 230 to wiper 231, thenceto the first contact on the fourth level and over conductor GM to cable205 to the lower winding of relay 255. Rela 255 operates, opens thecircuit to contactor 210 at contacts 255, and closes a holding circuitto its lower winding in series with the lower winding of relay 250 atcontacts 258. Contactor 210 restores and disconnects the 2300 v. A. C.supply from beacon light 272 at contacts 2'. In a similar manner, groundis extended through wiper I31 and the first bank contact on the fourthlevel of selector switch I03 and over conductor GM to operate a relaycorrespondingto relay 255 and thereby extinguish the indicatin lamp212'.

Key IGI is now restored causing relays E and 220 to restore and removegrounds from wiper I31 and relay I at contacts I22 and from wiper 231and relay 225 at contacts 224. When ground is removed from conductor C4Ia short-circuit is removed from the lower winding of relay 250 causingit to be energized in series with the lower winding of relay 255. Relay250 operates and transfers conductor C ll to the upper windings ofrelays 250 and 255 in multiple at contacts 25I. A similar operationtakes place in the miscellaneous light indicating relay group I05. Whenrelays I 20 and 220 restored they also reclosed the circuits to rotarymagnets H0 and 2l0 causing wipers I37 and 231 to rotate to the nextcontact but without efiect. Relays E25 and 225 subsequently restore andcomplete obvious circuits to the selector switch release magnets H8 and238 at contacts I20 and 233, respectively. The circuits to the rotarymagnets are also opened at the latter contacts. The release magnetsoperate to permit the selector switch shafts to restore to normal whenthe vertical ofi-normal springs restore to open the release magnetcircuits.

The boundary lights may be extinguished in the same manner by dialingthe number 31 assigned thereto. In this case wipers I31 and 233 will bestepped to the first contact in the third level to ground conductors C3Iand C34 Relay 285 will then be operated to release contactor 275. and acorresponding relay in the miscellaneous light indicating relay groupE05 will be operated to extinguish indicating lamp 271.

The beacon lights may be re-energized by again dialing 41. Whenconductor CM is grounded the second time a circuit is completed fromground over conductor C4I through contacts 25! directly to the upperwinding of relay 250, and through contacts 25'! to the upper Winding ofrelay 255. The latter relay is diiferentially wound and thereforerestores when both of its windings are energized, closes the circuit tocontactor 210 at contacts 255, opens the circuit to its upper winding atcontacts 251, and opens the circuit to its lower winding in series withthe lower winding of relay 255 at contacts 253. C'ontactor 275reoperates to close the circuit to beacon light 272 at contacts 2. Relay250 is held by its upper winding until ground is removed from conductorC4! by the restoration of relay 220. The second grounding of conductorC4! causes corresponding operations to take place in the miscellaneouslight indicating relay group I05 to reenergize lamp 212'. I

For the sake of simplicity only three groups of runway lights have beenshown. The system is arranged to permit selective energization of anyone of these three groups, or simultaneous energization of groups twoand three. All three groups of lamps are connected in series and eachgroup is normally short-circuited by contacts of a corresponding one ofthe contactors 540 to 550. Any one of these contactors may be operatedby the dispatcher by dialing the corresponding numbers 21 to 23, orcontactors 550 and 500 may be operated simultaneously by dialing 20, ina manner to be described presently. Operation of these contactors willhave no effect until the light intensity control relays are operated bydialing 51, 52 or 53, unless these relays have previously been operated.

If it is desired to cause the first group of runway lights RI to beenergized at a low value of current, either the corresponding runwaylight number 21 or the corresponding intensity number 51 may be dialedfirst. It will be assumed that 21 is dialed first and that no previousselection has been made. The dispatcher first operates key IM to theright and then proceeds to dial 21 by means of the impulse transmitterI02 to step the selector switches I03 and 203 to the first contact ofthe second level in the same manner as previously described. Selector203 then extends ground over conductor CZI of cable 405, throughcontacts 4I4, M0 and 472 to relay 490. Relay 490 operates; closes acircuit from one side of the v. A. C. supply over conductor 510, throughcontacts 49d, over conductor 542, and through contactor 540 to the otherside of the 110 v. A. C. supply; and closes a holding circuit to itselfthrough the upper winding of relay 410 and contacts 432 at contacts 432.When ground is removed from conductor C2I in response to the restorationof key IN a short circuit is removed from the upper winding of relay410, thus causing it to be energized in series with relay 490. Relay 410operates and closes a circuit to relay 4| 0 at contacts 474. Relay 4I0operates, closes a circuit to the lower winding of relay 445 from groundthrough contacts 493 at contacts 4| I, and opens points in the operatingcircuits to relays 480 and 405 at contacts 4I2 and M3, respectively.Relay 4| 5 operates and extends conductor C2! through contacts 4H and M0to relay 420. No further operations will take place in the runway lightcontrol relay group unless the number 21 is again dialed. Correspondingoperations take place in the runway light indicating relay group underthe control of selector switch !03 to cause lamp 540' to be energized.

The dispatcher now reoperates key Hill and dials 51 to cause selectorswitches I03 and 203 to step to the first contact on the fifth level andground conductors Gill and C54, respectively. The ground extended overconductor C5I energizes relay 380 through contacts 3M and 3'. Relay 380operates; closes a circuit from one side of the 110 v. A. C. supply overconductor 5' of cable 505, through contacts 38!, over conductor 5I2 ofcable 505, and through contactor 5I0 to the other side of the 110 v. A.C. supply; closes a holding circuit to itself through the lower windingof relay 3T0 and'contacts 323 at contacts 382; and closes a circuit fromground through contacts 32!, 303 and 320, over conductor 441, andthrough contacts MI, 494 and 443 to relay 445. Relay 445 operates andcloses a circuit to the lower winding of relay 440 at contacts 446.Relay 440 operates after a brief delay due to the slugging efiect of itsshort circuited upper winding, removes the short circuit from its upperwinding at contacts 442, and opens the circuit to relay 445 and closes alooking circuit to itself at contacts 443. Relay 445 is rendered slow torelease by a copper sleeve placed over its core. During the release timeof relay 445, contactor 5I0 operates over the above traced circuit andconnects winding 510a of transformer 510 across the secondary winding oftransformer 580 at contacts 5. Relay 445 subsequently restores andcloses a circuit to relay 435 through contacts 44I at contacts 440.Relay 435 operates and closes a circuit from one side of the 110 v. A.C. supply over conductor 510, through contacts 430, over conductor 502,and through contactor 500 to the other side of the 110 v. A. C. supply.Contactor 500 operates and closes a circuit to the primary winding oftransformer 580 from the 2300 v. A. C. supply at contacts 56!. When theprimary winding of transformer 580 is thus energized it produces aconstant current in its secondary winding, which current flows throughwinding 510a of transformer 510. The current induced in windings 510b, cand d will be equal to that flowing in winding 510a. divided by theratio between the total number of turns in windings 510b, c and d andthe number of turns in winding 510a, since the primary and secondaryampere-turns of a transformer are practically equal. The lightsassociated with the first runway are thus energized at a low value ofcurrent flowing through windings 510b, c and d of transformer 57!! andcontacts 55!, 56! and 5!!. The light intensity indicatin relay groupresponds to the ground extended over conductor C5! by selector switchN33 to energize lamp 510' in the same manner as light intensity controlrelays of Fig. 3 energized contactor 5I0.

The dispatcher restores key H]! to release the selector switches !03 and203 as previously described. When selector switch 203 removes groundfrom conductor C5! a short circuit is removed from the lower winding ofrelay 310 causing it to be energized in series with relay 385. Relay 310operates and closes a circuit to relay 3!!) from ground through contacts384 at contacts 313. Relay 3!0 operates, locks to ground throughcontacts 328 at contacts 3! and opens points in the operating circuitsto relays 340, 360 and 380 and transfers conductors C53, C52 and C5! torelay 320 through contacts 321 at contacts 3!2, 3l3 and 3l4.

If the dispatcher wishes to increase the current flowing through theenergized runway lights to a high value, he may do so by re-operatingkey and then dialing 53 to cause conductor C53 to be grounded byselector switch 203. The ground extended over conductor C53 energizesrelay 320 through contacts 3!2 and 321. Relay 320 operates and opens thecircuit to relay 440 and closes a circuit to relay 3!5 at contacts 32!.Relay 3I5 is a weighted spring relay of the type disclosed in Patent1,641,256, issued September 6, 1927, to John Erickson. When this relayoperates its weighted spring vibrates for several seconds, preventingimmediate operation of relay 325. During this delay interval relay 440restores and opens the circuit to relay 435 at contacts 44!. Relay 435restores and opens the circuit to contactor 500 at contacts 436.Contactor 500 restores and disconnects the 2300 v. A. C. supply fromtransformer 580 at contacts 50!. As the amplitude of vibration of theweighted spring of relay 3l5 decreases, the average current flowing inrelay 325 gradually increases until it is able to operate. When relay325 operates it opens the circuit to relay 320 at contacts 321 and opensthe holding circuit to relay 380 at contact 329. Relay 380 restores,opens the circuit to Contactor 510 at contacts 33!, and opens theoperating circuit to relay 3H1 at contacts 384. Relay 31!} remainsoperated due to the energization of its upper winding from ground overconductor C53 and through contacts 3!2, 3M and 312. Contactor H3restores. after a brief delay, opens the circuit to relay M5 at contacts32!, and opens the lockin circuit to relay 3!!! at contacts 322. Relay3! restores, opens the holding circuit to the upper winding of relay 310at contacts 3!4, and ex- Relay 320 restores tends the ground onconductor C53 to relay 340 through contacts 33! at contacts 3!2. Relay310 restores. Relay 340 operates, closes a circuit to contactor 530 overconductors 532 and 51! at contacts 34!, and closes a holding circuit toitself through the lower winding of relay 330 and contacts 322 atcontacts 342, Relay 325 restores and closes a. previously traced circuitto relay 445 over conductor 441 at contacts 326. Relays 445 and 440operate, relay 445 restores and relay 435 operates as previouslydescribed to close a circuit to contactor 500 over conductors 502 and510 at contacts 436 after a predetermined time interval. During thisinterval contactor 530 will have operated to connect windings 510a, band c of transformer 510 across the secondary of transformer 580 atcontacts 53!. Contactor 500 subsequently operates to reclose the 2300 v.A. C. supply circuit to the primary of transformer 580 at contacts 50!.The current now flowing through the energized runway lights will beequal to the constant current output of transformer 580 multiplied bythe ratio between the total number of turns in windings 510a b and c tothe number of turns in winding 510d. A high value of current is thusproduced in the circuit including winding 510d, runway lights RI, andcontacts 55!, 56! and 53!. The operations which take place in the lightintensity control relay group in response to the grounding of conductorC53 are duplicated in the light intensity indicating relay group !06 inresponse to the grounding of conductor C53 by selector switch !03. Lamp5!0' is thus extinguished and lamp 530 is energiZ-ed.

When the dispatcher restores key !0! the selector switches I03 and 203release, thereby removing grounds from conductors C53 and C53,respectively. The removal of ground from conductor C53 removes a shortcircuit from the lower winding of relay 330 causing it to be energizedin series with relay 340. Relay 330 operates and closes a circuit torelay 3!!! from ground through contacts 344 at contacts 333. Relay 3 6operates, locks to ground through contacts 328 at contacts 3! andextends conductors C5! to C53 to relay 320 through contacts 321 atcontacts (M2 to 3!4.

It will next be assumed that the dispatcher wishes to illuminate runwayNumber 3. As previously noted, no runway may be illuminated whileanother is illuminated. Thus if the dispatcher proceeded to operate keyill! to the right and then dialed the number 23 corresponding to runwaylights R3, conductor C23 would be grounded by selector switch 203 butwithout effect since the circuit between this conductor and relay 436 isopen at contacts M2. Therefore the dispatcher first dials the number 21to extinguish runway lights RI. When conductor C2! is grounded byselector switch 203 in response to the dialing of the number 21,circuits are completed from ground over conductor C2 through contacts41! and 413 to the lower winding of relay 410, through contacts 41!,4!!! and M6 to the upper winding of relay M5, and through contacts 41!and M9 to relay 420. Relay 420 operates, opens the circuit to relay 440at contacts 42!, closes a circuit to relay 425 at contacts 422, andlocks to ground through contacts 43! at contacts 423. Weighted springrelay 425 operates and closes an intermittent circuit to relay 436 atcontacts 426. Relays 440 and 435 and contactor 500 restore as previouslydescribed to de-energize transformer 580. Relay 430 subsequentlyoperates, opens the locking circuit to relay 420 at 9 contacts 43!, andopens th holding circuit to relay 490 through the upper winding of relay4'!!! at contacts 432. Relay 490 restores, opens the circuit tocontactor 540 at contacts 49 I, and opens the circuit to the lowerwinding of relay H5 at contacts 493. Contactor 54!! restores andshortcircuits runway lights R! at contacts 54 When selector switches H33and 243 are released by the restoration of key ground is removed fromconductor C2! thereby opening circuits to relay 420, the upper windingof relay 4 l 5, and the lower winding of relay 410. Relay 455 restores.Relay 470 restores and opens the circuit to relay M4 at contacts 474.Relay 424 restores and opens the circuit to relay 425 which restores andopens the circuit to relay 43B. Relay 4!!) restores and transfersconductors C2! to C23 to relays 49! 485 and 48!! at contacts 4M to M2,respectively. Relay 43E! restores.

When the dispatcher reoperates key I!!! and dials 23 selector switch 243grounds conductor C23 thereby completing a circuit to relay 489 throughcontacts 447, 4l2, 4!! and 452. Relay 48!) operates, closes a circuit tocontactor 566 over conductors 562 and Elli at contacts 44!, closes aholding circuit to itself through the upper winding of relay 450 andcontacts 432 at contacts 482, and-closes a circuit to relay 445 fromground over conductor 44'! at contacts 484. Relays 444 and 440 operate,relay 445 restores, and relay 435 operates to close a circuit tocontactor 5!!!! over conductors 502 and 51%! at contacts 435 after apredetermined time interval, as previously described. During, this timeinterval contactor 54!! operates to remove a short circuit from runwaylights R3 at contacts 35!. Contactor 5% subsequently operates toenergize transformer 546 from the 2,340 v. A. C. supply to illuminatethe runway lights R3. When selector switch 243 is released by therestoration of key llll, ground is removed from conductor C23 resultingin the energization of the upper winding of relay 454 in series withrelay 44!). Relay 459 operates, closes a circuit to relay' llll atcontacts 454, and opens a point in the operating circuit to relay 445 atcontacts 455-. Relay 4! t operates and closes a circuit to the lowerwinding of relay 4l5 from ground through contacts 433 at contacts 4iRelay 4l5 operates and extends conductor C243 through contacts 447, 45!and 4!! to relay 4%.

The system is arranged to permit concurrent illumination of runwaylights R2 and R3 since the second and third runways are non-interfering. To energize runway lights R2 and R3 simultaneously the dispatcherfirst dials the number corresponding to the runway lights which areenergized, in this case number 23, in order to extinguish them in thepreviously described manner, and then dials the number corresponding tothe combination of runway lights R2 and R3. The runway light controlrelays will have been restored to normal when the previously energizedrunway lights were extinguished so that when conductor C2!) is groundedby selector switch 243 in response to the dialing of number 20 a circuitis completed through contacts 455 and to the lower winding of relayRelay 445 operates, shunts contacts 455 and 455 at contacts 444, extendsconductor C24! to relay 484 through contacts 499, 44?, 4422, 4!! and452, and extends conductor C24 to relay 4% through contacts 449, 408,M3, 4! and 452. Relays 444 and 445 operate, close multiple circuits tothe upper winding of relay 445 through contacts 444 at contacts 483 and488, and close multiple circuits to relay 10 445 from ground overconductor 44'! at contacts 484 and 489.. Relay 480 also closes a circuitto contactor 560 over conductors 562 and 51!) at contacts 48!, andcloses a holding circuit to itself through the upper winding of relay459 and contacts 432 at contacts 482. Relay 4% also closes a circuit tocontactor 554 over conductors 552 and 5'!!! at contacts 486, and closesa holding circuit to itself through the upper winding of relay 464 andcontacts 432 at contacts 48?.

tactor 54! overconductors 542 and 574 at contacts 435 after apredetermined time interval during which contactors 554 and 56!! operateto remove short circuits from runway lights R2 and R3 at contacts 55!and 56!, respectively. When transformer 580 is energized in response tothe operation of contactor 544, runway lights R2 and R3 are energized inseries with each other and contacts 54! and 53! and winding 574d oftransformer 570. When ground is removed from conductor C24 in responseto the restoration of key 4! a short circuit is removed from the upperwindings of relays 458 and 464 causing them to be energized in serieswith relays 484i 2111:1484 in multiple with the lower winding of relay445. Relays 454 and 444 operate, open circuits to the lower winding ofrelay 445 at contacts 452and 442, and close multiple circuits to relayM4 at contacts 454 and 444. Relay 4M3 operates, closes a circuit to thelower winding of relay 4N? at contacts 4! from ground through contacts433 and 484 in multiple, and opens a point in the circuit to relay 494at contact-s 4l4. Relay 4B5 operates and extends multiple circuits fromconductor C20 to relay 424 through contacts 449, and 444,!and46!,and4!'!and4!li.

If the dispatcher wishes toextinguish one of the two energized groups ofrunway lights, he

must first dial 20 to extinguish both groups of lights and. must thendial the number corresponding to the group which it is desired shallremain energized. Selector switch 293 grounds conductor C29, in responseto the dialing of the number 20, thereby closing holding circuits to thelower winding of relay 495 through contacts 499, to the lower windingsof relays 454 and 464 through contacts 4B9, 40?, 45! and 453 and throughcontacts 459, 408, 46! and 463, and to the upper Winding of relay 415through contacts 449, 44'! and 488, 45! and 46!, 4!! and M8, and 4H5.Relay 42!? is energized in multiple with the upper winding of relay 4l5.When rela 424 operates it opens the circuit to relay 444 at contacts44!, closes a circuit to relay 425 at contacts 422, and locks to groundthrough contacts 43! at contacts 423. Weighted spring relay 425 operatesand closes an intermittent circuit to relay can at contacts 4245. Relays444 and 435 restore to release contactor 54!] and thereby de-energizetransformer 589. Relay 43! subsequently operates, opens the lockingcircuit to relay 42!] at contacts 43!, and opens the holding circuits torelays 484 and 485 through the upper windings of relays 454 and 454 atcontacts 432. Relays 484 and 485 rostore, open the circuits tocontactors 564 and 556 l at contacts 48! and 486, respectively, and openthe circuits to the upper winding of relay 4% and the lower winding ofrelay 4 5 at contacts 483 and 48B. Contactors 454 and 46!! restore. Whenselector 203 is released by the restoration of key it! ground is removedfrom conductor C24 thereby releasing relays 4!5, 424, 454 and 46B.Relays 454 and 4t!) restore and open multiple circuits to Relays 445,444 and 435 operate as 7 previously described to close the circuit toconrelay M at contacts 454 and 464. Relays 4H! and M5 restore. Relay 420restores and opens the circuit to relay 425 which restores and opens thecircuit to relay 430 at contacts 426. Relay 430 restores after a briefdelay. The operation of the runway light control relays in response tothe dialing of the number corresponding to the runway lights which it isdesired shall remain energized should be apparent from the precedingdescription.

It should be apparent that additional pairs of relays, such as 410 and490, may be added to control additional runway lights; and that, ifthere are more than two non-interfering runways, additional relays, suchas 405, may be provided to permit simultaneous con-tro1 of the runwaylights in different combinations.

In order to test the operation of the apparatus located at the switchingstation, the key 20I and impulse transmitter 202 are provided thereat.By operating key 20I to the right the circuit to relay 220 istransferred from conductors I08 and I09 to the 110 v. A. C. supplythrough the impulse transmitter 202. Selector 203 may then be controlledby the impulse transmitter 202 independently of the control station. Ifthe test man at the switching station wishes to converse with thedispatcher, key 20! is momentarily operated to the left therebycompleting a circuit from the 110 v. A. C. source over conductors I08and I09 to relay I40 in series with condenser H0 and contacts of keyIOI. Relay I40 operated momentarily, connects the 110 v. A. C. supply atthe control station to the ringer I04 at contacts I42, and opens a pointin the circuit to the handset I00 and locks to conductor I09independently of the talk ke I0! at contacts MI. The dispatcher respondsby operating key lIlI to the left thereby connecting the handset I00through contacts of key IIII, contacts I4I, over conductors I08 and I09,through contacts of key 20!, and through contacts MI and 22'! to thehandset 200 for two way conversation. Each handset is equipped with anon-locking switch which must be operated to complete a circuit to thetransmitter and receiver therein.

In the event of a failure of the direct current power supply (not shown)used to operate the relays at the switching station, relay 245 will bede-energized. Relay 245 restores, transfers conductor I08 from rectifier209 to one side of the 110 v. A. C. supply at contacts 246, connectscon- .ductor I09 to the other side of the 110 v. A. C.

supply at contacts 241, and connects alarm lamp 249 across the 110 v. A.C. supply at contacts 248. The connection of the 110 v. A. C. supply toconductors I08 and I09 causes relay I40 to operate and continuouslyenergize ringer I05 at the control station from the 110 v. A. C. supplythereat to notify the dispatcher of the failure.

The dispatcher may signal the test man at the switching station byoperating key Iii! to the right and dialing the number 01. Selectorswitch 203 operates in the previously described manner to extend groundthrough wiper 231 and the first contact on the tenth level to relay 240.Relay 24%! operates, opens a point in the circuit to handset 200 atcontacts 2M, and connects the 110 v. A. C. supply to ringer 204 atcontacts 242. Contacts 24I prevent the application of the the 110 v. A.C. signaling current to the transmitter and receiver of handset 200 inthe event that the test man operates the handset switch to answer beforethe circuit to relay 220 is interrupted in response to the restorationof key MI. Shortly after dialing 01 the dispatcher operates key IOI fromthe right to the left, thereby interrupting the operating circuit torelay 220 which restores to release the selector switch 203 and relay240. When relays 240 and 225 restore the previously traced communicatingcircuit between handsets I00 and 200 is completed.

What is claimed is:

1. An airport comprising a flying field having a plurality of airplanerunways thereon, illuminating means individually associated with saidrunways, a control circuit corresponding to each of said runways forcontrolling the illuminating means individually associated therewith, aselector switch having access to said control circuits, an electricsupply circuit for energizing said illuminating means, means common tosaid control circuits operated in response to selection thereof forautomatically rendering said electric supply circuit inactive, saidmeans automatically operated to activate said electric supply circuitafter a predetermined time interval.

2. An airport comprising a flying field having a plurality of airplanerunways thereon, illuminating means individually associated with saidrunways, an electric supply circuit for energizing said illuminatingmeans, a plurality of circuits for changing the intensity of saidilluminating means, a control circuit individual to each of saidintensity changing circuits and to each of said illuminating means, aselector switch having access to each of said control circuits, meansoperated in response to the selection of any of said control circuits bysaid selector switch for automatically rendering said electric supplycircuit inactive, said means automatically operated after apredetermined time to activate said electric suppliy circuit.

3. In an airport lighting system for an airport having a plurality ofrunways, a group of lamps individually associated with each of saidrunways, a control circuit for each of said groups, each control circuitincluding a control relay, an auxiliary relay, and a control lead, meansoperated to select any one of said control leads and to apply a controlpotential thereto, a circuit completed responsive to the selection andapplication of said potential to said selected control lead foroperating said control relay associated therewith, switching meansoperated in response to the operation of said control relay forilluminating a corresponding group of said lamps, means for removing thecontrol potential from said selected control lead in response to therelease of said first means, an auxiliary relay in said selected controlcircuit operated in response to the removal of said control potential, arelay common to said control circuits operated in response to theoperation of any one of said auxiliary relays to disable all of saidcontrol circuits except said selected control circuit, thereby, toprevent the operation of other of said control relays, means responsiveto the reapplication of said control potential to said selected controllead for releasing said operated control relay, thereby, to control saidswitching means to extinguish said illuminated group of lamps.

4. In an airport lighting system as claimed in claim 3 including circuitmeans for releasing said operated auxiliary relay and said common relayin response to the removal of the reapplied control potential from saidselected control lead by the subsequent release of said first means, thereleasing of said common relay 13 conditioning each one of said controlcircuits for subsequent individual operation.

5. In an airport lighting system having a group of lamps for marking arunway, means for illuminating said lamps, a selector switch, aplurality of intensity control circuits, each having a control leadindividually accessible to said selector switch, each one of saidcontrol circuits operable individually in. response to the selection ofthe corresponding control lead by said switch to determine a differentdegree of brilliance for said lamps, and any operated one of saidcontrol circuits remaining effective to determine the degree ofbrilliance until a subsequent selection of any one of said control leadsby said switch, a relay common to said control circuits, circuits foroperating said relay in response to the release of said selector switch,circuit releasing means, contacts on said relay operated to disconnectall of said control leads from their corresponding control circuits andfor connecting all of said control leads to said circuit releasingmeans, said circuit releasing means operated in response to thesubsequent selection of a different one of said control leads by saidswitch to release any operated one of said control circuits, said commonrelay released in response to the releasing of saidoperated controlcircuit to reconnect each one of said control leads to its correspondingcontrol circuit, and said control circuitcorresponding to the lastselected one of said control leads operated to determine a difi'erentdegree of brilliance for said illuminated lamps.

6. In an airport lighting system for illuminatinga plurality of runways,a group of lamps for each of said runways, a selector switch, a controlcircuit for each of said groups, each control circuit connected to anindividual control lead accessible to said selector switch, means tooperate said selector switch to select any one of said control circuits,any selected one of said control circuits operated individually inresponse to its selection to illuminate a corresponding group of saidlamps, relay means having a common control lead accessible to saidselector switch, said relay means operated in response to the selectionof said common control lead to disconnect a plurality of said individualcontrol leads that correspond to noneconflicting runways from theircontrol circuits and to connect said common control lead to saiddisconnected control circuits, said disconnected control circuitsoperated in response to their connection to said selected common controllead to illuminate the corresponding groups of lamps concurrently.

HARRY N. NEWSTEDT.

REFERENCES CITED The following references are of record in the file ofthis patent:

